[Offline Pages] Adds storage for kInvalidOfflineId.

chrome/browser/android/offline_pages/recent_tab_helper.cc

 // Copyright (c) 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/android/offline_pages/recent_tab_helper.h"
 
 #include <queue>
 #include <vector>
 
 #include "base/bind.h"
@@ skipping 134 matching lines @@
   if (!snapshots_enabled_)
     return;
 
   // We navigated to a different page, lets report progress to Background
   // Offliner.
   if (download_info_ && !navigation_handle->IsSamePage()) {
     ReportDownloadStatusToRequestCoordinator();
   }
 
   if (offline_pages::IsOffliningRecentPagesEnabled()) {
-    int64_t proposed_id = OfflinePageModel::kInvalidOfflineId;
     download_info_ = base::MakeUnique<DownloadPageInfo>(
-        GetRecentPagesClientId(), proposed_id);
+        GetRecentPagesClientId(), OfflinePageModel::kInvalidOfflineId);
   } else {
     download_info_.reset();
   }
 
   is_page_ready_for_snapshot_ = false;
 
   // New navigation, new snapshot session.
   snapshot_url_ = web_contents()->GetLastCommittedURL();
 
   // Check for conditions that would cause us not to snapshot.
@@ skipping 126 matching lines @@
 bool RecentTabHelper::IsSamePage() const {
   return web_contents() &&
          (web_contents()->GetLastCommittedURL() == snapshot_url_);
 }
 
 ClientId RecentTabHelper::GetRecentPagesClientId() const {
   return ClientId(kLastNNamespace, tab_id_);
 }
 
 }  // namespace offline_pages